Quick answer
Two habits, one blessed life: handle the word with attention and you find good; trust the LORD and you are happy. The proverb refuses to choose between them.
Read both lines
The first line commends careful weight given to instruction; finding good is the ordinary harvest of actually listening. The second goes deeper than technique: trust in the LORD, and the word is ashrei, happy, blessed, the congratulations of 3:13 and Psalm 1. The lines guard each other: heeding without trusting curdles into anxious rule-keeping; trusting without heeding drifts into sentiment that never opens the book. The blessed person does both at once, attentive to the word, at rest in the LORD who spoke it.
Related: Proverbs 3:5–6 · Psalm 1:1–3 · Jeremiah 17:7
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.